Calling



{No Model.)

F. R. McBERTY.

CALLING APPLIANCE FOR TELEPHONE SWITOHBOARDS.

Patented July 27, 189?.

flags UNITED STATES PATENT Orricn.

FRANK R.'MCBERTY, OF DOWNERS GROVE, ILLINOIS, ASSIGNOR TO THE' WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS.

CALLING APPLIANCE FOR TEILQEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 587,080, dated. July 27, 1897.

Application filed November 12, 1895. Serial No. 568,678. No model.) I

To all whom, it may concern:

Be it known that LFRANK R. MCBERTY, a

citizen of the United States, residing at Downers Grove, in the county of Du Page and State of Illinois, have invented a certain new and useful Improvement in Calling Appliances for,Telephone-Switchboards, (Case No. 33,) ofwhichthe following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention concerns the apparatus provi ded in switchboards of telephone-exchanges for transmitting selective signals in party telephone-lines. It is an arrangement of circuits and circuit-controlling switch-keys for connecting the source or sources of signalingcurrent with any one of several plug-circuits,

by which an economy of mechanism and increased facility of manipulation are attained.

In many systems of party-lines provided With signaling'instruments at the diifere'nt stations adapted for selective operation keys are furnished the operator attending the lines equal in number to the stations on a single line, each key being constructed to determine the operation of a particular signaling instrument only. It has been customary to connect a group of such keys in each of the several plug-circuits-usually fifteen-allotted to one operator, and another key has been placed in each of the plug-circuits controlling the connection of the operators telephone connect the operators telephone with one plug of a pair and to simultaneously connect the signal-transmitting keys with the other plug of the pair, and in another position to interrupt both these circuit connections, completing the plug-circuit directly between the two plugs. The operator may leave these listening-keys of her different plug-circuits inposition when the plugs are not in use to complete connection between the telephone and one plug of each of the pairs and between the signal-transmitting keys and the other plug of each pair. Then upon receiving a call from any line she will at once bring her telephone into connection with the callpair without the manipulation of any keys.

She will then operate the proper signalingkey to call the required station, after which she will move the listening-key of the plugcircuit used into position to complete it and to sever its connection with the telephone and with the signaling-keys. The use of this special listening-key, by means of which the disconnection of the signaling-keys is effected simultaneously with that of the telephone, is not essential in my invention, although it contributes to the utility of the device.

l The invention is shown in the accompanying drawing associated with a well-known system for selective signaling, comprising four signal-bells, which are connected in pairs with the two line conductors of a metallic circuit, the bells-connected with one line conductor being responsive to currents of opposite polarity. Four signaling-keys then con stitute the group, each adapted to transmit current of proper characterover a particular circuit to operate one of the bells. These keys are shown connected with two plug-circuits, this number being sufficient to illustrate the invention. A key for connecting the usual generator of signaling-current to operate the ordinary polarized bells is added to the group, and also a listening-key for occasional use in bringing the telephone into circuit with the calling-plug.

In the figure five substations A, B, C, D,

and E are represented, connected by two linc circuits with the usual apparatus in a switchboard. Station A is connected with the individual line 1 2. The line conductors appear in the contact-pieces of a spring-jack f in the switchboard, and include a visible signal or annunciator g and a battery h, the

spring-jack being constructed to interrupt the connection of the line with this apparatus during its use. The apparatus at the substation comprises the usual transmittingtelephone 1' and receiving-telephone t", a polarized bell i of high resistance, and a telephone-switch 1 which completes the line-circuit through the telephones when they arein position for use.

The stations B, C, D, and E are located on the party-line 3 4. This line-circuit is represented in the switchboard bya spring-jack f and by an annuneiator g, these line conductors being also connected with the battery h. These latter stations also are furnished with telephones i and 71', bells i and switches Each bell has a light spring acting upon its armature, tending to throw it to one of its extreme positions, so that it may be operated by a pulsating current of a particular direction only. The bells at stations B and C are connected in ground branches from the line conductor 4 and have their springs differently disposed, so that they require currents of opposite directions for their operation,negative and positive,respectively. The bells at stations D and E are in ground branches from line-wire 3, and are also adapted to be rung, the former by negatively and the latter by positively directed currents.

Two pairs of plugs It and k k are shown. The like contact-pieces of the members of each pair are connected by the conductors 5 and 6 of a plug-circuit. Each of the conductors of a plug-circuit includes, serially, two helices of an induction-coil l, and is connected at a point intermediate of the helices by a wire with a pole of battery It, the wires leading to the conductors 5 and 6 being designated 7 and 8, respectively. Each sleeve-conductor of a plug-circuit contains two visible signals m and m, one at each side of the induction-coil, so that one may be in circuit between the battery and each of two telephonelines united through the agency of the plugcircuit.

All the apparatus so far described is well known in the art of telephony.

- In this invention a listening-key n is included in each plug-circuit. This key has two pairs of switch-springs n n and n 71 between which oscillates a double-faced wedge n carried by the handle of the key. Each of the members of the former pair has a normal and an alternate contact-anvil, these being lettered in the drawing at n and n or", respectively. Each member of the latter pair of switch-springs has only a normal restingcontaet, the two being indicated by letters 71. and a When the lever is moved to thrust the wedge a between the springs 01/ and n these are raised from their normal anvils n and n and are forced against contacts a and a. At the same time springs 11 and n are permitted to rest on their anvils n and n. \Vhen wedge n is moved in the opposite direction, the springs of and n are raised from anvils a and n and springs '21 n are separated from contact-points n a and come to rest on anvils a M.

The portions of conductors 5 and 6 leading to the plug 70 terminate in contact-anvils n and n of this key and are connected with the switch-springs n and n Those portions of the same conductors which lead to plug 70 terminate in switch-springs 'n and n of the key. constitute open terminals of two wires 9 and 10, leading to the operators telephone 0. Contact-points n and n in all the keys form terminals of conductors 11 and 12, leading to the group of signaling-keys. These keys are of ordinary type, each with a pair of switchsprings oscillating between normal and alternate contacts. They are designated in the drawings a, b, c, d, and e in accordance with the designations of the stations whose bells they are intended to ring. added to the group for a purpose which will be explained later. One switch-spring and its resting-contact of each of these keys are included in each of the wires 11 and 12.. The alternate contacts of key a are the terminals of a signaling-generator q of alternating current. That alternate contact of key I) which is brought into connection with wire 11 and that of key d which is brought into connection with wire 12 are led to the negative terminal of a grounded generator 1'. This appliance is constructed to deliver pulsating currents of different directions to its brushes The resting contact anvils n and n.

A sixth key 17 is and is a well-known device for operating bells of the type here employed. The similar contact-points of keys 0 and care connected with the positive terminal of the same generator 1". The other contact of each of the keys is grounded. The alternate contacts of listening-key I) connect with the wires 9 and 10, leadingto the operators telephone.

The keys at 01": the plug-circuits which are not in use should be left with the wedges n thrust between the springs a n The plugs 70 or 70 which are denominated answeringplugs, being designed for use in answering calls, are then all connected with the operators telephone 0, and their connection with the other members 7:. or k is severed at points a 71 The calling-plugs 70 k are all connected with the group of signaling-keys. The operation of key a of this group will obviously permit an alternating current from generator q to flow out to all plugs k. The key I) when depressed will send a negative pulsating current to the tips of the plugs. Key 0 will send a positive current to the same parts. Keyd will send a negative and key e a positive current to the sleeves of the plugs. The key 19 may be used to connect the telephone 0 with telephone becomes connected with the line. Supposing the calling subscriber is at station A and that the required correspondent is at ing her telephone into circuit with the line.

Having signaled the correspondent, the operator places key it inposition to complete the plug-circuit between the members 10 and 7c of the pair used, whereby the telephone and the group of signaling-keys are at the same timeout off from the plug-circuit, leaving a complete circuitbetween the stations A and D. The supervisorysignals m and m serve to inform the attendant of the removal of the station-telephones from their switches and their replacement thereon at the termination of conversation. 1

The application of this invention thus permits the use of a single group of special calling-keys for a considerable number of pairs of plugs without necessitating additional manipulation of keys, and it eliminates the numerous switch-contactsof the special keys from the plug-circuit during its use in uniting lines. v

I claim as my invention- 1. The combination with telephone-lines, each provided with signaling appliances adapted for selective operation, several pairs of plugs for uniting lines, their associated plug-circuits, the operators telephone, of conductors and a group of keys each determining the transmission in the said conductors of a current adapted to operate a particular signal, and a key in each plug-circuit adapted to take either of two positions, said keybeing adapted when in one position to break the plug-circuit and to connect the telephone with one plug of the pair and the said conductors with the other plug of the pair, and in its other position to complete the plug-circuit, substantially as described.

2. The combination with telephone-lines and a return-circuit therefor, each having oppositely-polarized signal-bells in branches between each line conductor and the returncircuit, of several pairs of connecting-plugs for uniting diiferent telephonerlines, a key in each plug-circuit adapted to assume two positions, in one of which positions it severs the plug-circuit and connects the operators telephone Withone of the plugs and a pair of signaling-conductors with the other plug, and a group of keys connected with said signalingconductors, one adapted to send current of each polarity on each line conductor to operate a corresponding bell, as described.

In Witness whereof I hereunto subscribe my name this 1st day of October, A. D. 1895.

- FRANK R. MOBERTY.

Witnesses:

ELLA EDLER, WM. S. GRAMM. 

